I have a problem building output of add_custom_command in multiple projects causes unnecessary rebuild in Visual Studio. This problem is mentioned in the CMake documentation:
add_custom_command — CMake 3.5.1 Documentation https://cmake.org/cmake/help/v3.5/command/add_custom_command.html | Do not list the output in more than one independent target that may | build in parallel or the two instances of the rule may conflict | (instead use the add_custom_target() command to drive the command and | make the other targets depend on that one). But, the solution of using add_custom_target does not solve the problem. This is a simplified CMake script: | cmake_minimum_required(VERSION 3.5) | | project(hello VERSION 0.1 LANGUAGES CXX) | | add_custom_command(OUTPUT generated.cpp | COMMAND ${CMAKE_COMMAND} -E echo "int x;" > ${CMAKE_CURRENT_BINARY_DIR}/generated.cpp) | | add_executable(program_a | main_a.cxx | ${CMAKE_CURRENT_BINARY_DIR}/generated.cpp | ) | | add_executable(program_b | main_b.cxx | ${CMAKE_CURRENT_BINARY_DIR}/generated.cpp | ) | add_dependencies(program_b program_a) First time building ALL_BUILD, Visual Studio generates the generated.cpp in both projects program_a and program_b. Then, in the next time of ALL_BUILD, program_a is built because generated.cpp is updated after building program_a. Using add_custom_target does not solve the problem: | cmake_minimum_required(VERSION 3.5) | | project(hello VERSION 0.1 LANGUAGES CXX) | | add_custom_command(OUTPUT generated.cpp | COMMAND ${CMAKE_COMMAND} -E echo "int x;" > ${CMAKE_CURRENT_BINARY_DIR}/generated.cpp) | | add_custom_target(generate DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/generated.cpp) | | set_source_files_properties( | ${CMAKE_CURRENT_BINARY_DIR}/generated.cpp | PROPERTIES GENERATED 1) | | add_executable(program_a | main_a.cxx | ${CMAKE_CURRENT_BINARY_DIR}/generated.cpp | ) | add_dependencies(program_a generate) | | add_executable(program_b | main_b.cxx | ${CMAKE_CURRENT_BINARY_DIR}/generated.cpp | ) | add_dependencies(program_b program_a) | add_dependencies(program_b generate) In this case, the generated.cpp is generated in three project generate, program_a and program_b. program_a is built twice unnecessarily. Another example of using add_custom_target: | cmake_minimum_required(VERSION 3.5) | | project(hello VERSION 0.1 LANGUAGES CXX) | | add_custom_target(generate | COMMAND ${CMAKE_COMMAND} -E echo "int x;" > ${CMAKE_CURRENT_BINARY_DIR}/generated.cpp) | | set_source_files_properties( | ${CMAKE_CURRENT_BINARY_DIR}/generated.cpp | PROPERTIES GENERATED 1) | | add_executable(program_a | main_a.cxx | ${CMAKE_CURRENT_BINARY_DIR}/generated.add | ) | cpp_dependencies(program_a generate) | | add_executable(program_b | main_b.cxx | ${CMAKE_CURRENT_BINARY_DIR}/generated.cpp | ) | add_dependencies(program_b generate) | add_dependencies(program_b program_a) In this case, the generated.cpp is generated every time. Is there a way to specify not to invoke the custom command in program_a and program_b? I'm using Visual Studio 2015. -- Powered by www.kitware.com Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Kitware offers various services to support the CMake community. For more information on each offering, please visit: CMake Support: http://cmake.org/cmake/help/support.html CMake Consulting: http://cmake.org/cmake/help/consulting.html CMake Training Courses: http://cmake.org/cmake/help/training.html Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Follow this link to subscribe/unsubscribe: http://public.kitware.com/mailman/listinfo/cmake
